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Detection of microorganisms in different growth states based on microcalorimetry

A challenging test for establishing a rapid and reliable sterility method

Journal of Thermal Analysis and Calorimetry
Authors: Manrong Tan, Yongsheng Ren, Dan Yan, Xianghong Meng, Longhu Chen, Lingling Qiu, Yan Yan, Jianyu Li and Xiaohe Xiao

0.9% sterile sodium chloride solution. Then, the elution was diluted to the approximate concentration of 10 cfu. Take couple samples of 1.5 mL of the above-mentioned bacterium to 5 mL plastic tube individually, sealed up completely. One pot was

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European Journal of Microbiology and Immunology
Authors: E. Sapi, K. Gupta, K. Wawrzeniak, G. Gaur, J. Torres, K. Filush, A. Melillo and B. Zelger

respiratory pathogen whose infection leads to extra-pulmonary symptoms such as myocarditis, atherosclerosis, reactive arthritis, and nervous system disorders [ 58 , 59 ]. Chlamydia trachomatis is a bacterium responsible for causing sexually transmitted

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The antibacterial effect of the components of clary sage (Salvia sclarea L.) and spearmint (Mentha spicata L. var. crispa (Bentham) Danert) was investigated by means of high-performance thin-layer chromatography-direct bioautography against the Gram-positive soil bacterium Bacillus subtilis (Bs) and Gram-negative bacteria such as a pepper pathogen Xanthomonas euvesicatoria (Xe), a luminescence gene-tagged Arabidopsis pathogen Pseudomonas syringae pv. maculicola (Psm) and a luminescent marine Aliivibrio fischeri (Af). Sclareol, linalool, and linalyl acetate were identified as active components of clary sage and carvone as the antibacterial substance in spearmint. Sclareol inhibited all tested bacteria, linalool and carvone showed antibacterial effect against all Gram-negative strains tested, while linalyl acetate only against Xe and Af. Some minor components of the clary sage essential oil also gave a zone of inhibition when tested on Gram-negative bacterium strains.

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Acta Phytopathologica et Entomologica Hungarica
Authors: A. A. Czelleng, Z. Bozsó, P. G. Ott, E. Besenyei, G. J. Varga, Á. Szatmári, Y. M. Hafez and Z. Klement

Pseudomonas viridiflava is an opportunistic, post-harvest pathogenic bacterium that causes soft rot of fruits and vegetables. In vivo expression technology was used to identify genes that participate in the pathogenicity of P. viridiflava. Genetic loci that are induced in planta were identified. Ten such loci were partially sequenced and annotated. Here we describe five of them, which influence the pathogen's stress tolerance in planta. Three of the identified ORFs that show sequence identity to known genes encode membrane proteins, the remaining two encode enzymes in catabolic pathways.

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Acta Microbiologica et Immunologica Hungarica
Authors: Ana P. Rodrigues, A. R. M. Holanda, G. P. Lustosa, S. M. B. Nóbrega, Willma J. Santana, Luciana B. S. Souza and H. D. M. Coutinho

Serratia marcescens, a Gram-negative bacillus that belongs to the family Enterobacteriaceae, is a human opportunistic pathogen bacterium that causes many diseases, such as urinary tract infections, respiratory tract infections, bacteremia, conjunctivitis, endocarditis, meningitis and wound infections. Many plasmides that confers multi-drug resistance were discovered, such as virulence factors, like cytotoxins that damage epithelial cells. The main topic of this paper presents a review about the molecular traits evolved in the pathogenic processes mediated by Serratia and its mechanism of resistance to drugs.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: N. Tsibakhashvili, T. Kalabegishvili, L. Mosulishvili, E. Kirkesali, S. Kerkenjia, I. Murusidze, H. Holman, M. Frontasyeva and S. Gundorina

Abstract  

The dose-dependent formation of Cr(III) complexes and uptake of chromium by Arthrobacter oxydans — a Gram-positive bacterium from contaminated Columbian basalt rocks (USA) — were studied along with the testing under aerobic conditions of two bacterial strains of Arthrobacter genera isolated from the polluted basalts from the Republic of Georgia. Instrumental neutron activation analysis (INAA) was used to track the accumulation of chromium in the bacterial cells. To monitor and identify Cr(III) complexes in these bacteria, electron spin resonance (ESR) spectrometry was employed.

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Abstract  

The effect of Cr(VI) on Desulfovibrio vulgaris strain Hildenborough bioenergetic metabolism was monitored by microcalorimetry and the concomitant reduction of this metal was studied. Results showed that Cr(VI) is reduced by the bacterium and that the bacterial growth is altered, involving a strong modification of the metabolism of the bacteria. An absence of correlation between Cr(VI) reduction and cell growth is observed, suggesting that Cr(VI) does not yield energy to support anaerobic growth. The analysis of the enzymatic characteristics of Cr(VI) reduction are in progress.

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Abstract  

The power-time curves of the growth of three strains of petroleum bacteria at different temperatures have been determined. A novel equation of a power-time curve has been proposed in this paper. The general formula to calculate the rate constant of the bacterial growth has been derived. The rate constants of the bacterial growth at different temperatures, the heat production per newly formed bacterium, the bacterial number at the end of the bacterial growth and the deceleration rate constant of the bacterial growth at 50.00°C, have been calculated. The optimum growth temperatures of the three strains have been obtained.

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The aim of the present study was the chemical characterization of some medically relevant essential oils (tea tree, clove, cinnamon bark, thyme, and eucalyptus) and the investigation of antibacterial effect of the components of these oils by use of a direct bioautographic method. Thin-layer chromatography (TLC) was combined with biological detection in this process. The chemical composition of the oils was determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Eucalyptol (84.2%) was the main component of the essential oil of eucalyptus, eugenol (83.7%) of clove oil, and trans-cinnamic aldehyde (73.2%), thymol (49.9%), and terpinen-4-ol (45.8%) of cinnamon bark, thyme and tea tree oils, respectively. Antibacterial activity of the separated components of these oils as well as of their pure main components (eucalyptol, eugenol, trans-cinnamic aldehyde and thymol) was observed against the Gram-negative luminescence gene-tagged plant pathogenic bacterium Pseudomonas syringae pv. maculicola (Psmlux) and the Gram-negative, naturally luminescent marine bacterium Vibrio fischeri. On the whole, the antibacterial activity of the essential oils could be related to their main components, but the minor constituents may be involved in this process. trans-Cinnamic aldehyde and eugenol were the most active compounds in TLC-bioautography. The sensitivity of TLC-bioautographic method can be improved by using luminescent test bacteria. This method is more cost-effective and provides more reliable results in comparison with conventional microbiological methods, e.g., disc-diffusion technique.

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Bacillus thuringiensis ssp. israelensis (Bti) is increasingly used as an ecologically friendly anti-mosquito agent. The bacterium cells undergo fermentation in dilute suspensions; before practical use, therefore it is necessary to concentrate the suspensions. Aggregation by polymers is a powerful tool with which to regulate the stability of suspensions. Typically, polymers at low concentrations destabilize and at high concentrations stabilize colloidal systems. Bti suspensions can be flocculated efficiently by either cationic or anionic polyelectrolytes. Cationic polyelectolytes were found to be the most efficient flocculants for bacterial suspensions. It was shown that the degree of toxicity of the flocculated Bti suspensions for biting mosquito larvae was in the same range than in non-flocculated suspension.

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